The objective of this study was to monitor changes in ovarian status in heifers exposed to a
progesterone insert with or without concurrent gonadotropin-releasing hormone (GnRH) injection.
Estrus was manipulated in 283 ...

Lactating dairy cows and replacement virgin heifers of unknown pregnancy status were treated
with either gonadotropin-releasing hormone (GnRH) or saline to initiate a resynchronization
program that was continued 7 days ...